Combining QCD Matrix Elements at Next-to-Leading Order with Parton Showers in Electroproduction

We present a method to combine next-to-leading order (NLO) matrix elements in QCD with leading logarithmic parton showers by applying a suitably modified version of the phase-space-slicing method. The method consists of subsuming the NLO corrections into a scale-dependent phase-space-slicing parameter, which is then automatically adjusted to cut out the leading order, virtual, soft and collinear contributions in the matrix element calculation. In this way a positive NLO weight is obtained, which can be redistributed by a parton shower algortihm. As an example, we display the method for single-jet inclusive cross sections at O(alpha_s) in electroproduction. We numerically compare the modified version of the phase-space-slicing method with the standard approach and find very good agreement on the percent level.Comment: 21 pages, 2 eps figures. Revised section 2. To appear in PR

Has the QCD RG-Improved Parton Content of Virtual Photons been Observed?

It is demonstrated that present $e^+e^-$ and DIS ep data on the structure of the virtual photon can be understood entirely in terms of the standard `naive' quark--parton model box approach. Thus the QCD renormalization group (RG) improved parton distributions of virtual photons, in particular their gluonic component, have not yet been observed. The appropriate kinematical regions for their future observation are pointed out as well as suitable measurements which may demonstrate their relevance.Comment: 24 pages, LaTeX, 5 figure

Atualização do levantamento de reconhecimento de solos dos municípios da Bacia do Paraná 3 e Palotina.

Os municípios formadores da Bacia do Paraná 3 (BP3) e o município de Palotina, todos localizados no Terceiro Planalto Paranaense, foram o objeto do presente estudo. Em boa parte dessas paisagens predominam solos com boas características para a agricultura industrial conexa à produção intensiva de grãos e de proteína animal. O setor primário e a agroindústria dos municípios geram riquezas que sustentam o desenvolvimento regional em níveis muito superiores à média nacional, justificando a iniciativa da atualização do levantamento de solos aqui apresentado, considerando que a espacialização dos solos é ferramenta essencial à definição de políticas de planejamento de uso da terra. Assim, o presente trabalho objetivou atualizar, no perímetro de abrangência dos municípios da BP3 e Palotina, o mapa de solos gerado por Bhering e Santos (2008), considerando: resoluções da 5a edição do Sistema Brasileiro de Classificação de Solos (Santos et al., 2018), ampla checagem de nomeação das unidades de mapeamento (realizada polígono a polígono), reagrupamento das unidades de mapeamento de solos e qualificação das unidades de mapeamento em atributos de retenção de água (incluindo viagens de campo, coleta de amostras e análises de retenção de água). São partes interativas desse estudo o presente relatório, o mapa de solos na escala 1:250.000 e os arquivos shapes que formam a base de dados cartográfica em ambiente de Sistema Geográfico de Informações. Características gerais da região são apresentadas por Gomes et al. (2020)

Factorization Breaking in Dijet Photoproduction with a Leading Neutron

The production of dijets with a leading neutron in ep-interactions at HERA is calculated in leading order and next-to-leading order of perturbative QCD using a pion-exchange model. Differential cross sections for deep-inelastic scattering (DIS) and photoproduction are presented as a function of several kinematic variables. By comparing the theoretical predictions for DIS dijets to recent H1 data, the pion flux factor together with the parton distribution functions of the pion is determined. The dijet cross sections in photoproduction show factorization breaking if compared to the H1 photoproduction data. The suppression factor is S = 0.48 (0.64) for resolved (global) suppression.Comment: 16 pages, 5 figure

Coherent Parton Showers with Local Recoils

We outline a new formalism for dipole-type parton showers which maintain exact energy-momentum conservation at each step of the evolution. Particular emphasis is put on the coherence properties, the level at which recoil effects do enter and the role of transverse momentum generation from initial state radiation. The formulated algorithm is shown to correctly incorporate coherence for soft gluon radiation. Furthermore, it is well suited for easing matching to next-to-leading order calculations.Comment: 24 pages, 3 figure

Standard Model Large-E_T Processes and Searches for New Physics at HERA

Existing and missing calculations of standard model processes producing large transverse energy in electron-proton interactions at HERA are reviewed. The adequacy of the existing standard model Monte Carlo programs for generic searches of exotic processes is analyzed.Comment: 9 pages, LaTeX, uses iop style files, Contribution to the 3rd UK Phenomenology Workshop on HERA Physics, September 1998, Durha

HERA Physics Beyond the Standard Model

The prospects of physics beyond the standard model in deep inelastic scattering are reviewed, emphasizing some scenarios which attained attention after the observation of an excess of events with large momentum transfer at HERA.Comment: 8 pages, LaTeX, uses iop style files and axodraw.sty, Talk presented at the 3rd UK Phenomenology Workshop on HERA Physics, September 1998, Durha

Hadronic final states in deep-inelastic scattering with Sherpa

We extend the multi-purpose Monte-Carlo event generator Sherpa to include processes in deeply inelastic lepton-nucleon scattering. Hadronic final states in this kinematical setting are characterised by the presence of multiple kinematical scales, which were up to now accounted for only by specific resummations in individual kinematical regions. Using an extension of the recently introduced method for merging truncated parton showers with higher-order tree-level matrix elements, it is possible to obtain predictions which are reliable in all kinematical limits. Different hadronic final states, defined by jets or individual hadrons, in deep-inelastic scattering are analysed and the corresponding results are compared to HERA data. The various sources of theoretical uncertainties of the approach are discussed and quantified. The extension to deeply inelastic processes provides the opportunity to validate the merging of matrix elements and parton showers in multi-scale kinematics inaccessible in other collider environments. It also allows to use HERA data on hadronic final states in the tuning of hadronisation models.Comment: 32 pages, 22 figure

The histone demethylase Jumonji domain-containing protein 3 (JMJD3) regulates fibroblast activation in systemic sclerosis.

OBJECTIVES: Systemic sclerosis (SSc) fibroblasts remain activated even in the absence of exogenous stimuli. Epigenetic alterations are thought to play a role for this endogenous activation. Trimethylation of histone H3 on lysine 27 (H3K27me3) is regulated by Jumonji domain-containing protein 3 (JMJD3) and ubiquitously transcribed tetratricopeptide repeat on chromosome X (UTX) in a therapeutically targetable manner. The aim of this study was to explore H3K27me3 demethylases as potential targets for the treatment of fibrosis. METHODS: JMJD3 was inactivated by small interfering RNA-mediated knockdown and by pharmacological inhibition with GSKJ4. The effects of targeted inactivation of JMJD3 were analysed in cultured fibroblasts and in the murine models of bleomycin-induced and topoisomerase-I (topoI)-induced fibrosis. H3K27me3 at the FRA2 promoter was analysed by ChIP. RESULTS: The expression of JMJD3, but not of UTX, was increased in fibroblasts in SSc skin and in experimental fibrosis in a transforming growth factor beta (TGFβ)-dependent manner. Inactivation of JMJD3 reversed the activated fibroblast phenotype in SSc fibroblasts and prevented the activation of healthy dermal fibroblasts by TGFβ. Pharmacological inhibition of JMJD3 ameliorated bleomycin-induced and topoI-induced fibrosis in well-tolerated doses. JMJD3 regulated fibroblast activation in a FRA2-dependent manner: Inactivation of JMJD3 reduced the expression of FRA2 by inducing accumulation of H3K27me3 at the FRA2 promoter. Moreover, the antifibrotic effects of JMJD3 inhibition were reduced on knockdown of FRA2. CONCLUSION: We present first evidence for a deregulation of JMJD3 in SSc. JMJD3 modulates fibroblast activation by regulating the levels of H3K27me3 at the promoter of FRA2. Targeted inhibition of JMJD3 limits the aberrant activation of SSc fibroblasts and exerts antifibrotic effects in two murine models

PYTHIA 6.4 Physics and Manual

The PYTHIA program can be used to generate high-energy-physics `events', i.e. sets of outgoing particles produced in the interactions between two incoming particles. The objective is to provide as accurate as possible a representation of event properties in a wide range of reactions, within and beyond the Standard Model, with emphasis on those where strong interactions play a role, directly or indirectly, and therefore multihadronic final states are produced. The physics is then not understood well enough to give an exact description; instead the program has to be based on a combination of analytical results and various QCD-based models. This physics input is summarized here, for areas such as hard subprocesses, initial- and final-state parton showers, underlying events and beam remnants, fragmentation and decays, and much more. Furthermore, extensive information is provided on all program elements: subroutines and functions, switches and parameters, and particle and process data. This should allow the user to tailor the generation task to the topics of interest.Comment: 576 pages, no figures, uses JHEP3.cls. The code and further information may be found on the PYTHIA web page: http://www.thep.lu.se/~torbjorn/Pythia.html Changes in version 2: Mistakenly deleted section heading for "Physics Processes" reinserted, affecting section numbering. Minor updates to take into account referee comments and new colour reconnection option